Methods and apparatus of enhancing performance in wireless communication systems

ABSTRACT

Methods and apparatus for supporting and using multiple communications channels corresponding to different transmit technologies and/or access technologies in parallel within a cell of a wireless communications system are described. Mobile nodes support multiple technologies and can switch between the technology being used at a particular point in time, e.g., from a first channel corresponding to a first technology to a second channel corresponding to a different technology which provides better transmission characteristics, e.g., a better perceived channel quality. Mobiles maintain at least two sets of channel quality information at any one point in time. Mobiles select the better channel and communicate the channel selection to the base station or communicate channel quality information for multiple channels to the base station and allow the base station to select the channel corresponding to the technology providing the better conditions for the mobile. Different mobiles in the same cell may support different technologies.

RELATED APPLICATIONS

The present application is a divisional of pending U.S. patentapplication Ser. No. 11/599,837, filed on Nov. 15, 2006 titled “METHODSAND APPARATUS OF ENHANCING PERFORMANCE IN WIRELESS COMMUNICATIONSYSTEMS” which is a continuation of U.S. patent application Ser. No.10/830,976, filed on Apr. 23, 2004, titled “METHODS AND APPARATUS OFENHANCING PERFORMANCE IN WIRELESS COMMUNICATION SYSTEMS” which issued asU.S. Pat. No. 7,142,864 and which claims the benefit of U.S. ProvisionalApplication Ser. No. 60/464,823 filed on Apr. 23, 2003. U.S. patentapplication Ser. No. 11/599,837 is hereby expressly incorporated byreference in its entirety.

FIELD

The present invention relates to wireless communications methods andapparatus and, more particularly, to methods and apparatus for usingmultiple communications techniques on a dynamically selected basis tocommunicate with one or more devices.

BACKGROUND

In a wireless multiple access communication system, a base station isresponsible for communicating with multiple users. In general, thecondition and characteristics of the wireless communication channelbetween a user and the base station can vary quite a lot from one userto another. The reason is that while channel fading is an ubiquitousphenomenon occurring in most wireless channels, the nature of the fadingprocess can vary widely. For example, users who are moving rapidlyexperience fast fading, which can be challenging for the transmitter totrack. On the other hand, stationary or pedestrian users normallyexperience channels with very slow fading that can be tracked accuratelyby the transmitter using feedback from the receiver. As the transmissiontechniques for achieving optimum performance depend on the condition andcharacteristics of channels on which communication takes place, it maybe infeasible to have a single technique that performs well for allchannel scenarios.

Several advanced communication techniques have been proposed forstate-of-the-art wireless communication systems, many of which usemultiple antennas at the transmitter and sometimes at the receiver. Somecommunication techniques are optimized for situations where thetransmitter has multiple antennas while the receiver is constrained tohave a single antenna. Within this category, some techniques, such asthe Alamouti scheme, are optimized for receivers that perceive rapidlyfading channels that can be tracked at the receiver but not at thetransmitter. The Alamouti scheme is described in S. M. Alamouti, “Asimple transmitter diversity scheme for wireless communications,” IEEEJournal on Selected Areas in Communication, vol. 16, pp. 1451-1458,October 1998. There is a whole family of techniques, generally referredto as MIMO (multiple-input, multiple-output) techniques that areapplicable in situations where the transmitter as well as the receiverhave multiple antennas and can form a matrix channel. Some of thesetechniques are described in 1) V. Tarokh, N. Seshadri and R. Calderbank,“Space-time codes for high data rate wireless communication: Performancecriterion and code construction,” IEEE transactions on InformationTheory, vol. 44, pp. 744-765, March 1998 and 2) A. Naguib, N. Seshadriand R. Calderbank, “Increasing data rate over wireless channels,” IEEESignal Processing Magazine, May 2000. These can, in general, extendperformance along two dimensions. They can either be used for providingadditional diversity (diversity gain), or they can be used to increasethe data rate by establishing parallel data streams between transmit andreceive antennas (spatial multiplexing). In general, a given space-timecoding technique offers some diversity gain and some spatialmultiplexing gain.

While different transmission technologies may provide benefits to oneset of users in a multi-user system, other technologies may be bettersuited for providing signals to another set of users in the system.Furthermore, which technology provides the best method for supplyinginformation to a user may change over time, e.g., as the user moves fromone location to another and/or a users rate of movement changes withtime. Accordingly, there is a need for methods and apparatus forproviding a mobile user the benefits of a particular technology at apoint in time which best suits the mobile's needs, receptioncharacteristics and/or other mobile related characteristics such asmotion characteristics, at the particular point in time. In addition, ina multi-user system, in would be desirable to be able to providedifferent wireless terminals, e.g., mobile devices, in a cell

SUMMARY

Given the mix of users in a wireless communication system, it may not bedesirable to use a transmission technique that is optimized for a singleparticular category of users. This use of one transmission technique forall classes of users may constrain the performance of the system.

The present invention is directed to methods and apparatus for takingadvantage of the transmission benefits which can be achieved bysupporting a plurality of different communications technologies at abase station or other common node which interacts using wirelesscommunications channels with one or more wireless terminals, e.g.,mobile nodes. The different communications technologies may be differenttransmission technologies which involve, e.g., different ways ofcontrolling antenna patterns and/or different, access technologies.Access technologies are frequently defined in engineering or other fixedstandards which are, in many cases, publicly available.

In accordance with the present invention a base station supportsmultiple communications channels which are sometimes referred to hereinas pipes. The quality of the communication channel, and thus itscapacity to communicate information, is normally a function of both theamount of resources allocated to the particular channel and the type oftechnology used to implement the channel. Physical conditions such assignal interference may also affect wireless transmission and thus thequality of a channel. However, the effect of physical conditions on achannel will often differ depending on the type of access technologyused to implement the particular communications channel.

In accordance with one embodiment of the present invention, a basestation supports multiple channels corresponding to differenttechnologies at any particular point in time. The channels may be fixedand remain unchanged over long periods of time, e.g., multiple periodsin which one or more mobile nodes are scheduled to use thecommunications channel. Alternatively, some or all of the channels maybe periodic in nature with channels corresponding to differenttechnologies being maintained at different points in time, e.g., in arepeating predictable manner resulting in different channel combinationsexisting at various points in time. In addition and/or as an alternativeto using a fixed set of communications channels corresponding todifferent accesses technologies in parallel, a base station may operateto allocate resources to channels corresponding to channelscorresponding to different technologies in a dynamic fashion. Forexample, in some embodiments, in response to a mobile node indicating aselection of a channel corresponding to a particular technology to beused to the base station or the base station selecting to supportcommunications with the mobile node using a particular communicationstechnology, the base station may create a channel corresponding to theselected communications technology and/or increase the allocation ofresources to an existing channel corresponding to the electedcommunications technology, e.g., to increase the amount of time theselected technology is used and to thereby increase the number ofchannel segments corresponding to a particular transmission technology.

The communications technologies which are used to create communicationschannels may, and often are, incompatible. For example communicationover communications channel created with different incompatibletechnologies may require physical and/or signal processing changes inthe receiver and/or transmitter when changing from a communicationschannel corresponding to a first technology to a communications channelimplemented using a second technology which is incompatible with thefirst technology. This is because particular technologies may imposephysical and/or other constraints such as specific hardwareconfiguration requirements, such as the number of antennas used, whichhave to be satisfied for successful receipt and/or transmission ofsignals corresponding to the particular technology. Communicationstechnologies are often defined by communications standards published byone or more standards bodies. Two communications technologies defined bycommunications standards may be considered incompatible when compliancewith the communications standard which defines or specifies therequirements for one communications technology would result in atransmission, reception or other constraint or operation which wouldviolate a requirement specified in the standard which defines orotherwise specifies the requirements for the other of the twocommunications technologies.

A system implemented in accordance with the invention normally includesat least one communications cell but will more commonly include multiplecells. Each cell includes at least one base station. A plurality ofwireless terminals, e.g., mobile devices, normally communicate with thebase station at any given point in time, e.g., using segments of one ormore communications channels. Given that different communicationschannels use different communications channels, to take advantage of thebenefits of the diversity provided by supporting multiple communicationstechnologies at the same time or in a periodic predictable manner whichuses different technologies at recurring time intervals, at least somewireless terminals support multiple technologies. For example, awireless terminal may be capable of supporting OFDM and CDMAcommunications. While some wireless terminals support multipletechnologies, other wireless terminals may support only one technology.For example, some wireless terminals may include a single receiveantenna while other wireless terminals may include multiple receiveantennas. The wireless terminals which include multiple receive antennasmay can switch between communications channels which use MIMO andrequire multiple receive antennas and channels which correspond totechnologies which use a single receive antenna. Wireless terminals witha single receive antenna would use the channel or channels which areimplemented using the single receive antenna technologies and wouldstill be able to interact with the base station but would not be able totake advantage of the channels require multiple receive antennas.

In order to support an intelligent selection of which channel to use ata particular time, each wireless terminal which supports multipletechnologies maintains a set of quality information, e.g., SNRinformation, for at least two channels implemented using two different,e.g., incompatible, technologies. In some implementations, the wirelessterminal selects between the plurality of channels based on whichchannel is indicated to provide the better quality at a particular pointin time as indicated, e.g., by a comparison of the quality informationcorresponding to the different channels. In one such embodiment thewireless terminal transmits a signal to the base station indicating thetechnology and/or channel corresponding to a particular technology whichthe wireless terminal has determined will provide the desired qualitylevel. In other embodiments, the wireless terminal transmits a signal tothe base station providing quality information on at least two channelsimplemented using different technologies. The base station then selectsthe channel which is implemented using a technology which will providethe wireless terminal a desired level of performance. The base stationselection channel selection method is particularly beneficial wheremultiple channels may provide a suitable quality level to the wirelessterminal and the base station considers channel loading in addition tothe reported channel quality information when making a channel selectionwith regard to the channel to be used to communicate with a particularwireless terminal.

In some embodiments, the mobility of the mobile node is taken intoconsideration when deciding what technology to use to communicate withthe mobile node. In cases where the mobile node is moving at a highspeed, the channel is likely to be changing at a relatively high rate.The speed of motion by a wireless terminal is sometimes estimated basedon the rate of fading, a measured Doppler shift, or other signals suchas the rate of changes in the power level of a periodic signal receivedform a wireless terminal or the rate and/or amount of timing correctionsmade by a wireless terminal or signaled to the wireless terminal.

When a channel changes at a high rate, the rate at which a wirelessterminal feeds back channel condition information to a base stationshould also be high, e.g., so that the information is not highlyinaccurate by the time it is received and/or acted upon. In a wirelesssystem, where conservation of communications bandwidth is often animportant consideration, in the case of rapid movement of a wirelessterminal, it may be desirable to use a communications technology whichuses little or no channel condition feedback, e.g., to adjust theantenna transmission pattern.

In cases where wireless terminal motion is zero or relatively slow, beamforming techniques which use feedback information from the wirelessterminals at the base station to control antenna patterns may be highlydesirable.

Accordingly, in some embodiments of the invention the wireless terminalsestimate their rate of motion or the base station makes a motiondetermination using one or more of the above described techniques orvarious other techniques such as using Global Positioning Satellite(GPS) information to detect changes in position. The rate of motion isthen used in some embodiments to detect the communications channel whichis implemented using the communications technology which is best suitedfor the particular measured or estimated rate of motion. In some cases,this involves selecting a channel which uses a technology which requireslittle or no channel condition feedback information for a wirelessterminal moving at a fast rate and selecting a communications channelwhich uses a faster channel condition feedback rate when the wirelessterminal is moving at a slower rate. Different motion rate thresholdsmay be used in a wireless terminal to select between communicationschannels corresponding to different communications technologies so thatthe technology used can be best matched to the wireless terminals rateof motion which, in the case of a station terminal will be zero.

In addition to physical issues, the type of data to be transmitted andthe amount of data may affect the selection of a channel correspondingto a particular technology. For example, some technologies may be bettersuited to voice traffic which may require a continuous or nearcontinuous connection and/or flow of data for extended period of timewhile other technologies may be better suited to short bursty datatransmissions where minimal set up time may be beneficial.

In view of the above discussion, it should be appreciated that wirelessterminals capable of supporting multiple different communicationstechnologies can obtain benefits by switching between channelsimplemented using various different, and often incompatible,communications technologies. This allows a wireless terminal to obtainthe benefit of using the best or at least a suitable supportedtechnology for a particular given situation. Examples of differentaccess technologies which may be supported by a wireless terminal inaccordance with the invention include CDMA, OFDM, and narrowband signalcarrier technologies. Access technologies defined in various WiFistandards and/or other communications standards may also be supported.

Numerous additional benefits, embodiments and features of the presentinvention are described in the detailed description which follows.

BRIEF DESCRIPTION OF THE FIGURES

FIGS. 1-3 illustrate various communications channels which may be usedto communicate between a wireless terminal and a base station inaccordance with the invention.

FIG. 4 is a graph illustrating the channel variations a mobile receivermay perceive when the base station uses a single opportunistic beam.

FIG. 5 is a graph 500 illustrating the channel variations perceived by amobile receiver when the base station uses two opportunistic beams thatare offset in phase.

FIG. 6 illustrates exemplary embodiments of using parallel pipes in CDMAand OFDM systems.

FIG. 7 is a graph illustrating parallel pipes that may be used in anexemplary CDMA or OFDM system implemented in accordance with theinvention.

FIG. 8 illustrates dynamically shared traffic segments.

FIG. 9 is a drawing 900 illustrating the correspondence betweenassignment and traffic segments.

FIG. 10 is a drawing illustrating acknowledgements sent in response totraffic segments received.

FIG. 11 shows an alternative embodiment where the technique used in agiven pipe can be changed dynamically from time to time.

FIG. 12 illustrates the use of different transmit powers on differentpipes.

FIG. 13 illustrates an exemplary communications system 10 implemented inaccordance with the invention.

FIG. 14 illustrates an exemplary access router, e.g., base station 12,implemented in accordance with the invention.

FIG. 15 illustrates an exemplary mobile node 14 implemented inaccordance with the present invention.

FIG. 16 is an illustration of an exemplary wireless communicationssystem 1600, implemented in accordance with the present invention.

FIG. 17 illustrates an exemplary base station implemented in accordancewith the present invention.

FIG. 18 illustrates an exemplary wireless terminal implemented inaccordance with the present invention.

FIG. 19 is a flowchart illustrating an exemplary communications methodin accordance with the present invention.

FIG. 20 illustrates a method performed by a wireless terminal inaccordance with one exemplary embodiment of the invention.

FIG. 21 illustrates a method performed by a base station in accordancewith one embodiment of the invention.

DETAILED DESCRIPTION

This invention discloses methods and apparatus to enhance the overallperformance of a wireless multiuser communication system using multipletransmit antennas. The methods and apparatus of the present inventionmay be used in systems such as the ones described in U.S. patent Ser.No. 09/691,766, filed Oct. 18, 2000 which is hereby expresslyincorporated be reference. Communications systems in which the inventionmay be used often typically feature communication to and from multiplewireless users whose channel conditions and characteristics can varysignificantly from one user to another. The remainder of thisdescription, for purposes of explaining the invention, will be presentedin the context of an exemplary cellular wireless system. However, theinvention is sufficiently fundamental that its advantages may berealized in other flavors of wireless communication systems, e.g.,non-cellular systems, as well.

This invention realizes significant benefits in the downlink (from thebase station to mobile users) as well as the uplink (mobile userstransmitting to the base station) channels of cellular wireless systems.The description below focuses on the downlink but it should beunderstood that the technique is general in nature and is applicable tothe uplink as well in systems where a mobile, e.g., wireless terminal,has multiple transmit antennas.

The central idea of this invention is the creation of multiple parallel‘pipes’ by the subdivision of the available transmission resources in asystem, and the realization of different transmission techniques usingmultiple transmit antennas in these pipes.

In accordance with this invention, a “pipe” is most generally apartition of the available air link resource. The available degrees offreedom are partitioned into several pipes such that the receiver canmeasure the wireless channel quality on any of the parallel pipesindependently. The partition can be done in any particular way, such asin frequency, in time, or in code, or some combination of these.

In general, the construction of the pipes can be in a frequency or timedivision manner or in a combined time/frequency manner. The embodimentin FIG. 1 constructs the parallel pipes by partitioning the air linkresource in frequency. FIG. 1 is a graph 100 of frequency on verticalaxis 102 vs time on horizontal axis 104. FIG. 1 includes four downlinkparallel pipes A 106, B 108, C 110 and D 112. Pipe A 106 includes twodisjoint frequency segments 106A, 106B and may represent a pipe for highmobility uses. Pipe B 108, pipe C 110, and pipe D 112 each include asingle frequency segment and may represent pipes for low mobility users.FIG. 2 shows another embodiment where parallel pipes are obtained bypartitioning the air link resource in time. FIG. 2 is a graph 200 offrequency on the vertical axis 202 vs time on the horizontal axis 204.FIG. 2 includes four segments 206, 208, 210, and 212, where each segment206, 208, 210, 212 occupies the same frequency range, but a differenttime slot. The two embodiments shown in FIG. 1 and FIG. 2 can be mixedto lead to another embodiment as shown in FIG. 3, where both frequencydivision and time division to construct parallel pipes. FIG. 3 is agraph 300 of frequency on the vertical axis 302 vs time on thehorizontal axis 304. FIG. 3 illustrates four physical frequency bands, afirst physical frequency band 306, a second physical frequency band 308,a third physical frequency band 310, and a fourth physical frequencyband 312, FIG. 3 also illustrates three time slots, a first time slot314, a second time slot 316, and a third time slot 318. In FIG. 3, eachpipe 320, 322, 324, 326 while defined in a particular logical frequencyextent occupies a different physical frequency band from one time slotto the next. Different types of shading are used to distinguish betweendifferent pipes in FIG. 3 with different frequency time blocks with thesame shading corresponding to the same pipe. Pipe 320 occupies:frequency band 312 in first time slot 314, frequency band 308 in secondtime slot 316, and frequency band 306 in third time slot 318. Pipe 322occupies: frequency band 310 in first time slot 314, frequency band 306in second time slot 316, and frequency bands 312 and 308 in third timeslot 318. Pipe 324 occupies: frequency band 308 in first time slot 314and frequency band 310 in second time slot 316. Pipe 326 occupies:frequency band 306 in first time slot 314, frequency band 312 in secondtime slot 316, and frequency band 310 in third time slot 318. FIG. 6illustrates exemplary embodiments of using parallel pipes in CDMA andOFDM systems. FIG. 6 is a drawing 600 illustrating three pipes, pipe 1602, pipe 2 604, and pipe 3 606 in an exemplary CDMA system. Drawing 600includes a horizontal axis 608 representing frequency. The exemplaryCDMA system has a 5 MHz bandwidth 610 in total, which is partitionedinto three carriers 603, 605, 607, each representing a 1.25 MHz pipe,resulting in a total of 3 pipes (Pipe 1 602, pipe 2 604, pipe 3 606).Thus, there are three parallel pipes 602, 604, 606 in that 5 MHz CDMAsystem. FIG. 6 also includes a drawing 650 illustrating multiple pipesin an exemplary OFDM system. Drawing 650 includes a horizontal axis 652representing frequency. The illustrated OFDM system also has a 5 MHzbandwidth 654 in total, which is divided into N tones where verticalarrows 656 are used to represent individual tones. In FIG. 6, those Ntones 656 are grouped into four subsets 658, 660, 662, 664. FIG. 650includes three parallel pipes 666, 668, 670. First parallel pipe 666includes two tone subsets 658 and 664. Second parallel pipe 668 includeone tone subset 660. Third parallel pipe 670 includes one tone subset662. Thus, there are three parallel pipes in that 5 MHz OFDM system.

FIG. 7 is a graph 700 of frequency on the vertical axis 702 vs time onthe horizontal axis 704 illustrating parallel pipes that may be used inan exemplary CDMA or OFDM system. In FIG. 7 the illustrated CDMA or OFDMsystem has a 1.25 MHz bandwidth 706 in total, which is shared by twoparallel pipes 708, 710 in a time division manner. Different shading isused to indicate the components of the different pipes 708, 710 withhorizontal lines being used to indicate components of one pipe andvertical lines to indicate components of the other pipe. Pipe 1 708occupies the 1.25 MHz BW from time t₀ 712 to t₁ 714 and from time t₂ 716to t₃ 718. Pipe 2 710 occupies the 1.2.5 MHz BW from time t₁ 714 to t₂716 and from time t₃ 718 to t₄ 720.

Each of the pipes formed in this manner is associated with a specificuse of the multiple transmit antennas available at the transmitter. Ingeneral, the different pipes use the available antennas differently. Thetransmission technique within a pipe may be optimized for a certaincategory of wireless channel characteristics and, in general, suits acertain category of users. A desirable characteristic of thispartitioning is that wireless receivers should be able to monitorchannel conditions corresponding to each pipe independently. One waythis may be achieved, for example, is to transmit pilots independentlyin each of the pipes to facilitate channel estimation.

An exemplary embodiment of the invention is described below in thecontext of a cellular wireless data communication system. The exemplarysystem is similar to the systems disclosed in U.S. patent applicationSer. Nos. 09/706,377 and 09/706,132, which are hereby incorporated byreference. The exemplary system includes modifications to the systemsdescribed in the referenced applications which cause the exemplarysystem to implement the present invention. While an exemplary wirelesssystem is used for purposes of explaining the invention, the inventionis broader in scope than the example and can be applied, in general, tomany other communication systems as well.

In a wireless data communication system, the air link resource generallyincludes bandwidth, time or power. The air link resource that transportsdata and/or voice traffic is called the traffic channel. Data iscommunicated over the traffic channel in traffic channel segments(traffic segments for short). Traffic segments may serve as the basic orminimum units of the available traffic channel resources. Downlinktraffic segments transport data traffic from the base station to thewireless terminals, while uplink traffic segments transport data trafficfrom the wireless terminals to the base station. One system to which thepresent invention may be applied is the spread spectrum OFDM (orthogonalfrequency division multiplexing) multiple-access system disclosed inU.S. patent application Ser. No. 09/267,471.

In the exemplary system used here to explain the invention, a trafficsegment includes of a number of frequency tones over a finite timeinterval. Each of the parallel pipes includes traffic segments that canbe shared dynamically among the wireless terminals that arecommunicating with a base station. A scheduling function is a module inthe base station that assigns each uplink and downlink traffic segmentto one (or more) of the mobile terminals based on a number of criteria.A given traffic segment can be entirely contained in one pipe or moregenerally it can occupy resources in more than one pipe or even each ofthe pipes. The transmitter and receiver know the structure of trafficsegments in the pipes.

The allocation of traffic segments to users is done on asegment-by-segment basis and different segments can be allocated todifferent users. FIG. 8 is a drawing 800 illustrating dynamically sharedtraffic segments. FIG. 8 includes a vertical axis 802 representingfrequency vs a horizontal axis 804 representing time, and is used forplotting exemplary traffic segments. For example, in FIG. 8, segment A806, having vertical lines for shading, is assigned to user #1 by thebase station scheduler and segment B 808, having horizontal lines forshading, is assigned to user #2. The base station scheduler can rapidlyassign the traffic channel segments to different users according totheir traffic needs and channel conditions. The allocation of channelsegments may be time varying in general. The traffic channel is thuseffectively shared and dynamically allocated among different users on asegment-by-segment basis.

In the exemplary system of the present invention, the assignmentinformation of downlink (and uplink) traffic channel segments to usersis transported in the assignment channel, which includes a series ofassignment segments. Each traffic segment is associated with a uniqueassignment segment. An assignment segment can, and in some embodimentsdoes, convey assignment information about one or more traffic segments.The assignment segment associated with one or more given trafficsegment(s) conveys the assignment information for the associated trafficsegment(s). The assignment information may include the identifier of theuser terminal(s), which is assigned to utilize the associated trafficsegment(s), and also the coding and modulation scheme to be used in theassociated traffic segment(s). FIG. 9 is a drawing 900 illustrating thecorrespondence between assignment and traffic segments. FIG. 9 includesa vertical axis 902 representing frequency vs a horizontal axis 904representing time, and is used for plotting exemplary assignment andtraffic segments. For example, FIG. 9 shows two assignment segments, A′906 and B′ 908, which convey the assignment information corresponding tothe associated traffic segments A 910 and B 912, respectively. Theassignment channel is a shared channel resource. The users receive theassignment information conveyed in the assignment channel and thenutilize the traffic channel segments according to the assignmentinformation. Assignment segments could be contained in any one pipe ormore generally be split across many or each of the pipes to providemaximum diversity.

Data transmitted by the base station on a downlink traffic segment isdecoded by a receiver in the intended wireless terminal while datatransmitted by the assigned wireless terminal on the uplink segment isdecoded by a receiver in the base station. Typically the transmittedsegment includes redundant bits that help the receiver determine if thedata is decoded correctly. This is done because the wireless channel maybe unreliable and data traffic, to be useful, typically has highintegrity requirements.

Because of interference, noise and/or channel fading in a wirelesssystem, the transmission of a traffic segment may succeed or fail. Inthe exemplary system of the present invention, the receiver of a trafficsegment sends an acknowledgment to indicate whether the segment has beenreceived correctly. The acknowledgment information corresponding totraffic channel segments is transported in the acknowledgment channel,which includes a series of acknowledgment segments. Each traffic segmentis associated with a unique acknowledgment segment. For a downlinktraffic segment, the acknowledgment segment is in the uplink. For anuplink traffic segment, the acknowledgment segment is in the downlink.At the minimum, the acknowledgment segment conveys one-bit ofinformation, e.g., a bit, indicating whether the associated trafficsegment has been received correctly or not. Because of the predeterminedassociation between uplink traffic segments and acknowledgementsegments, there may be no need to convey other information such as theuser identifier or segment index in an acknowledgment segment.Acknowledgement segments could be included in any one pipe or moregenerally be split across many or each of the pipes to provide maximumdiversity.

An acknowledgment segment is normally used by the user terminal thatutilizes the associated traffic segment and not other user terminals.Thus, in both the links (uplink and downlink) the acknowledgment channelis a shared resource, as it can be used by multiple users, e.g., withdifferent users using different segments at different times. While beinga shared resource, there is no contention that results from the use ofthe acknowledgment channel, as there is no ambiguity in which userterminal is to use a particular acknowledgement segment. FIG. 10 is adrawing 1000 illustrating acknowledgements sent in response to trafficsegments received. FIG. 10 includes a drawing 1002 of frequency on thevertical axis 1004 vs time on the horizontal axis 1006 used forillustrating downlink traffic segments. In drawing 1002, exemplarydownlink traffic segment A 1008 and exemplary downlink traffic segment B1010 are shown. FIG. 10 also includes a drawing 1052 of frequency on thevertical axis 1054 vs time on the horizontal axis 1056 used forillustrating acknowledgements segments of an uplink acknowledgementsegment channel that may be used to transmit acknowledgement signalssent in response to received downlink traffic segment signals. Drawing1052 of FIG. 10 shows two uplink acknowledgment segments, A″ 1058 and B″1060, which convey the acknowledgment information of downlink trafficsegments A 1008 and B 1010.

FIG. 1 illustrates a basic embodiment of the invention in the frameworkof the exemplary OFDM system described above. In this embodiment, theavailable bandwidth is divided in frequency into four parallel pipes,labeled as ‘A’ 106, ‘B’ 108, ‘C’ 110 and ‘D’ 112, which can be used toserve different users simultaneously. Each of the pipes 106, 108, 110,112 is associated with its own two-antenna transmission technique aswill be described below. Extension to more than two antennas ispossible.

The spread-spectrum properties of the exemplary OFDM system are obtainedby allowing logical tones to periodically hop in a pseudo-random manneracross the available bandwidth. In the context of this invention, eachof the parallel pipes could maintain a spread-spectrum property withinthe bandwidth in which it is defined. Tones used in all the channelsdefined in a particular pipe are hopped in a pseudo-random manner acrossthe frequency band/bands in which the pipe is defined. More generally,the logical tones in the system could hop across the bandwidth resourcesof two or more pipes.

In accordance with the invention, the measurement of the channel qualityof each of the parallel pipes should be facilitated. In the context ofthe exemplary system, pilot tones can be used to facilitate channelquality measurements. Channel quality measurements may includesignal-to-interference ratio (SIR) and fading characteristics. In thisembodiment, each parallel pipe contains its own pilot tones. Thedensities of pilots used in each pipe can be varied to suit thetransmission technique employed as will be discussed below. In oneexemplary embodiment, the mobile receiver estimates the channel qualityon the pipes. Based on the channel quality estimates, the receiver thendetermines the best pipe to receive the data traffic segments on. Themobile receiver then reports this pipe selection along with the channelquality estimate on the pipe to the base station. The structure of thechannel estimate report may be different for different pipes dependingon the transmission technique used in the pipe.

The independent channel estimation of multiple parallel pipesfacilitates the pipe selection process. This concept allows the mobilereceiver to perform pipe selection in cooperation with the base stationtransmitter.

In a more general setting, a user receiver may determine that the besttraffic segments for it to receive data are the ones that are splitacross two or more pipes. In this case the mobile receiver indicatesthis selection of traffic segments to the base station along with thechannel quality estimate. Here the channel quality estimate is formedbased on the channel quality estimates of the corresponding pipes thatthe segments are split across.

The base station as well as the mobile terminals may use a commoncontrol channel in addition to traffic data and assignment channels. Thecontrol channel may be used to communicate power control and/or othercontrol information. The control channel resources could be entirelyincluded in one pipe or, more generally, be split into two or morepipes.

In the example illustration in FIG. 1, pipe A 106 is formed from twonon-contiguous bands 106A and 106 B while pipes B 108, C 110 and D 112are each formed from resources in a contiguous band of spectrum. Theidea behind having many pipes is to use the two available base stationtransmit antennas differently in each pipe on that different pipeslikely have different channel quality for different user terminals. InFIG. 1, pipes ‘B’ 108, ‘C’ 110 and ‘D’ 112 are optimized fortransmission to user terminals whose channel is varying relativelyslowly compared with the frequency of channel quality feedback and thusthe channel quality can be tracked reliably at the base station, e.g.,low mobility or stationary users. In this scenario, the technique ofswitched opportunistic beamforming is complemented with intelligentscheduling that exploits multi-user diversity is a natural application.Opportunistic beamforming as described in U.S. Provisional patentapplication Ser. No. 09/691,766 which is hereby incorporated byreference, is a technique that is used to exploit multiuser diversity inscenarios where mobile users experience quasi-static or slowly varyingchannels. In this technique, the base station transmitter uses multipletransmit antennas to deliberately create channel fluctuations which canbe exploited by an opportunistic scheduler to increase system capacity.In switched opportunistic beamforming, the base station transmitter hasthe additional advantage of being able to create independentopportunistic beams in multiple parallel pipes. The mobile receivers cantrack the variations of the wireless channel over all the pipes andreport, a preferred pipe back to the base station along with the channelquality on that pipe. The induced channel variations can be coordinatedbetween the parallel pipes in such a manner that it is very likely thatat least one of the pipes is substantially better than the others. Thistechnique can realize the available transmit diversity gain offered bytwo transmit antennas along with any available frequency diversity gainplus beamforming gain. In a cellular deployment where different basestations use the same (or similar) pipe structure, a user terminal islikely to select a pipe which has a good channel to the desired basestation and a not so good channel to the interfering base station. Theresulting additional gain is termed as opportunistic cell coordinationgain. In the remaining part of this description, the pipes denoted ‘B’108, C′ 110 and ‘D’ 112 will be referred to as ‘opportunisticbeamforming pipes’ and it is assumed that they can use the switchedopportunistic beamforming technique described in U.S. Provisional patentapplication Ser. No. 09/691,766 which is hereby incorporated byreference including each of the generalizations of the technique.

The concept of switched opportunistic beamforming may be motivated usingan example using two transmit antennas. FIG. 4 is a graph 400illustrates the channel variations perceived by a mobile receiver whenthe base station uses a single opportunistic beam. Graph 400 includes avertical axis 402 representing received SNR, a horizontal axis 404representing time in slots, and a plot 406 of SNR experienced by areceiver with a single opportunistic beam. FIG. 5 is a graph 500illustrating the channel variations perceived by a mobile receiver whenthe base station uses two opportunistic beams that are offset in phase.In FIG. 5, the base station produces two opportunistic beams ondifferent pipes that are offset in phase from each other. Graph 500includes a vertical axis 502 representing received SNR, a horizontalaxis 504 representing time in slots, a plot 506 of SNR experienced by areceiver with respect to beam 1, and a plot 508 of SNR experienced by areceiver with respect to beam 2. The receiver sees the channel qualityvarying over time on any particular pipe and, in general, perceives highchannel quality on one of the pipes (and corresponding beams) whenanother pipe (and corresponding beam) offer low channel quality, asillustrated in FIG. 4 and FIG. 5. It is easy to see that using two beamscan effectively reduce the latency at the receiver in waiting for a timeinstant when the channel quality is high and the receiver can selectbetween the beams depending on their channel qualities. The receiver isin a position to select the strongest among these beams and report thepipe associated with the selected beam (and the corresponding channelquality) to the transmitter, such that the transmitter can send trafficto the receiver with the pipe of the best channel quality.

In the context of this invention, assume that the base stationtransmitter uses two antennas in each of pipes ‘B’ 108, ‘C’ 110 and ‘D’112 for the purpose of creating opportunistic beams. Consider a mobilereceiver and denote the time-varying channel responses from the twotransmit antennas to that receiver as h_(α)(t) and h_(β)(t)respectively. For clarity of description, it is assumed that the channelresponse from either antenna to the receiver is constant acrossfrequency, and hence constant across the multiple pipes. However, thisassumption does not diminish or constrain the invention in any way. Let{α₁(t), α₂ (t), α₃ (t)} and {β₁(t), β₂(t), β₃(t)} be time-varyingcoefficients used to modulate the signals on the first and secondantenna respectively in the pipes ‘B’ 108, C′ 110 and ‘D’ 112. If thesignals to be transmitted over the opportunistic beamforming pipes aredenoted byS (t)={S _(B)(t),S _(C)(t),S _(D)(t)},then the actual physical signals that are transmitted over the pipesfrom the two antennas can be represented byS ⁽¹⁾ (t)={α₁(t)S _(B)(t),α₂(t)S _(C)(t)α₃(t)S _(C)(t)}S ⁽²⁾ (t)={β₁(t)S _(B)(t),β₂(t)S _(C)(t)β₃(t)S _(C)(t)}

Therefore, the signals received by the receiver in the opportunisticbeamforming pipes are given byR _(B)(t)=S _(B)(t)[h _(α)(t)α₁(t)+h _(β)(t)β₁(t)]R _(C)(t)=S _(C)(t)[h _(α)(t)α₂(t)+h _(β)(t)β₂(t)]R _(D)(t)=S _(D)(t)[h _(α)(t)α₃(t)+h _(β)(t)β₃(t)]

Hence, when the invention is applied to the system with two transmitantennas and multiple parallel pipes, the composite channel response ink-th parallel pipe from the transmitter to the receiver is effectivelygiven by α_(k)(t)h_(α)(t)+β_(k)(t)h_(β)(t).

With a suitable choice of the values of the coefficients {α_(k)(t)} and{β_(k)(t)} at the transmitter, at least one of the opportunisticbeamforming pipes will likely have higher composite channel quality thanthe composite channel responses of the other pipes. The choice of thecoefficients {α_(k)(t), β_(k)(t)} is quite flexible. In one embodiment,{α_(k)(t)} is set to a constant, {β_(k)(t)} is set to be aconstant-amplitude complex number with phase being rotated with time:α_(k)(t)=1β_(k)(t)=exp(j2πf _(rot) t+ν _(k))where the phase offsets {ν_(k)} are uniformly distributed in [0,2π]. Inthis example, since there are pipes employing opportunistic beamforming,the phase offsets may be chosen as ν₁=0,

${\upsilon_{2} = \frac{2\pi}{3}},{\upsilon_{3} = {\frac{4\pi}{3}.}}$This particular embodiment results in three opportunistic beams thateach rotates with frequency f_(rot). In general, these phase offsetsneed not be uniformly distributed as described above. The offset betweenthe beams may even be changed at a slow rate in order to optimize thesystem for a particular spatial distribution of users.

In the more general case β_(k) could also be a function of frequency, inparticular β_(k)(t, f)=exp(j2πf_(rot)+j2πΔf+ν_(k)), where Δ representsdelay in one antenna's signal over the other. This generalization alsocovers the case where the signal transmitted from one of the antennas onpipes B 108, C 110 and D 112 is simply a delayed version of the signaltransmitted on the other antenna. This delay results in a frequencyselective fading of the channel at the receiver. In other words, somepart of the band covering pipes B 108, C 110 and D 112 has destructiveinterference at the receiver from the two signals and other part of theband may have constructive interference. Consequently a pipe included inthe part of the band where the signals from the two antennas addconstructively has better channel quality than other pipes where thesignal adds destructively. By selecting the best pipe in this case theuser terminal can realize beamforming gain.

In another embodiment, each of the pipes may effectively be transmittedon a subset of the available antennas. For example, in the case wherethere are two transmit antennas, each pipe may be transmitted using oneof the antennas. This may be achieved by setting the magnitudes of(α_(k), β_(k)) to be close to (1,0) or (0,1). The mobile terminals mayperceive higher channel quality with respect to either of the antennasand thus select an appropriate pipe and report this selection to thebase station. Further, this choice of pipe can vary dynamically withtime as the channels with respect to the transmit antennas change.

The idea of the switched opportunistic beamforming paradigm is that thetransmitter sends multiple offset beams on different pipes, the receiverindependently measures the channel qualities of the parallel pipes andreports to the transmitter the best pipe and measurement results on thatpipe. The transmitter sends traffic to the receiver on that pipe. Tobenefit from switched opportunistic beamforming the receiver does notneed to estimate h_(α)(t) and h_(β)(t) explicitly, but is only requiredto measure the aggregate SNR on the pipes.

Having the choice of pipes B 108, C 110 and D 112 helps those userswhose channel quality can be tracked at the transmitter. For users thatmove fast the channel quality cannot always be tracked at the basestation transmitter because of delay in the feedback. These users maynot benefit from the switched opportunistic beamforming scheme describedabove. In this situation, diversity techniques that serve to increasediversity gain by averaging across multiple, independent fadingprocesses are suitable. Many such techniques typically only require thatthe channel be estimated and tracked at the receiver and no feedback tothe transmitter is needed.

Pipe A 106 in FIG. 1 can be optimized to serve this category of users.One space-time code that can be used in pipe A 106 to provide transmitdiversity gain in accordance with the invention is the Alamouti schemedescribed in S. M. Alamouti, “A simple transmitter diversity scheme forwireless communications,” IEEE Journal on Selected Areas inCommunication, vol. 16, pp. 1451-1458, October 1998. In this technique,two transmit antennas are employed in the following manner. Assume thatthe pipe denoted ‘A’ 106 has two transmit antennas. Let the signal thatis communicated over the pipe be denoted by S(t) where t is assumed tobe a discrete time instant. In the Alamouti scheme, two consecutivesymbols are blocked off and transmitted over two time instants using thetwo antennas. Let X₁(t) and X₂(t) represent the output signals from thetwo antennas respectively, which may be expressed as

$\begin{bmatrix}{X_{1}(t)} & {X_{1}\left( {t + 1} \right)} \\{X_{2}(t)} & {X_{2}\left( {t + 1} \right)}\end{bmatrix} = \begin{bmatrix}{S(t)} & {- {S^{*}\left( {t + 1} \right)}} \\{S\left( {t + 1} \right)} & {S^{*}(t)}\end{bmatrix}$

Suppose that the time-varying channel responses from the two antennas tothe mobile receiver are denoted by h₁(t) and h₂(t) respectively (forsimplicity we assume a flat channel but more general case where thechannel is frequency dependent can also be handled easily). If thechannel coefficients are assumed to remain constant over two symbols,which is a mild assumption, the composite signal received by the mobilereceiver can be represented byY(t)=h ₁ X ₁(t)+h ₂ X ₂(t)+W(t)Y(t+1)=h ₁ X ₁(t+1)+h ₂ X ₂(t+1)+W(t+1)which may be rewritten in terms of the original signal S(t) as

$\begin{bmatrix}{Y(t)} \\{Y\left( {t + 1} \right)}\end{bmatrix} = \begin{bmatrix}{{h_{1}{S(t)}} + {h_{2}{S\left( {t + 1} \right)}} + {W(t)}} \\{{{- h_{1}}{S^{*}\left( {t + 1} \right)}} + {h_{2}{S^{*}(t)}} + {W\left( {t + 1} \right)}}\end{bmatrix}$or alternative

$\begin{bmatrix}{Y(t)} \\{Y^{*}\left( {t + 1} \right)}\end{bmatrix} = {{\begin{bmatrix}h_{1} & h_{2} \\h_{2}^{*} & {- h_{1}^{*}}\end{bmatrix}\begin{bmatrix}{S(t)} \\{S\left( {t + 1} \right)}\end{bmatrix}} + \begin{bmatrix}{W(t)} \\{W^{*}\left( {t + 1} \right)}\end{bmatrix}}$

If the channel responses from the two antennas are known, it isstraightforward to invert the transmitter code construction and extractthe transmitted signal by the following transformation:

$\begin{bmatrix}{\hat{S}(t)} \\{\hat{S}\left( {t + 1} \right)}\end{bmatrix} = {{\begin{bmatrix}h_{1}^{*} & h_{2} \\{- h_{2}} & h_{1}\end{bmatrix}\begin{bmatrix}{Y(t)} \\{Y\left( {t + 1} \right)}\end{bmatrix}} = {{\left( {{h_{1}}^{2} + {h_{2}}^{2}} \right)\begin{bmatrix}{S(t)} \\{- {S\left( {t + 1} \right)}}\end{bmatrix}} + {noise}}}$which results in second-order diversity over a fading channel.

In addition to the transmit diversity technique employed, frequencydiversity can help to combat frequency-selective fading. For thisreason, the pipe denoted ‘A’ 106 is located in such a manner that it isdefined over two parts 106A, 106B that are separated in frequency. Thetransmitted data is coded jointly over the two parts 106A, 106B thatcomprise pipe ‘A’ 106. With the Alamouti scheme employed using twotransmit antennas at the base station and data coded across two pipeparts separated in frequency by more than the coherence bandwidth of thewireless channel, the mobile receiver can see fourth order diversitywhich sufficiently compensates for the rapidly fading channel.

In order that the channel response from each of the transmit antennas beestimated at the mobile receiver, pipe ‘A’ 106 allows for two sets ofpilot tones. One set is transmitted only from the first antenna whilethe second set is transmitted from the second antenna.

In the basic embodiment, each mobile receiver monitors its own channelcharacteristics in the different pipes and makes a selection. The userterminal reports this selection back to the base station along withproper channel condition feedback. For example, if the user determinesthat it is of low mobility, it may select the best of the opportunisticbeamforming pipes B 108, C 110 or D 112 and report the aggregate SNRreceived on the preferred pipe. If the user is in a high mobilitysituation and experiences rapid fading, it indicates a choice of pipe A106 which employs the Alamouti technique to the base station along withthe channel quality on pipe A 106. The base station scheduler may chooseto allocate a traffic segment to this user over the selected pipe, inwhich case the user is notified through the assignment channel.

The techniques illustrated in this basic embodiment are onlyrepresentative of the potential of this invention. To reiterate, theinvention allows for the creation of different pipes and the employmentof different multiple antenna transmit techniques within those pipes inconjunction with receiver selection diversity.

There can be a number ways of generalizing the above basic embodiment.Some of the generalization schemes are discussed below.

In one scheme, the transmit techniques that are used in individual pipesare dynamically changed. In the embodiment of FIG. 1, the choice oftechniques in individual pipes is fixed and is known by the users servedby the base station. FIG. 11 shows an alternative embodiment where thetechnique used in a given pipe can be changed dynamically from time totime. FIG. 11 is a drawing 1100 of frequency on the vertical axis 1102vs time on the horizontal axis 1104. Available bandwidth is subdividedinto physical frequency bands, A 1106, B 1108, C 1110, D 1112, and E1114. The time domain is subdivided in slots, slot 1 1116, slot 2 1118.During time slot 1 1116, each frequency band A 1106, E 1114 represents apipe for a high mobility user 1120, while each frequency band B 1108, C1110, and D 1112 represents a pipe for a low mobility user 1122. Duringtime slot 2 1118, each frequency band A 1106, D 1112, E 1114 representsa pipe for a high mobility user 1120, while each frequency band B 1108,C 1110 represents a pipe for a low mobility user 1122, in thatembodiment, the base station may broadcast the choice of the techniqueperiodically. The two embodiments shown in FIG. 1 and FIG. 11 can bemixed to lead to another embodiment where some pipes use fixedtechniques while others use techniques that can dynamically vary.

In another generalization scheme, the decision of which pipe to use fora given user can also be made at the base station. In this case insteadof reporting the decision, the user may just report the preference ofwhich pipe to use, and it is up to the base station to determine whichpipe to actually serve the user. The user terminal may actually evenreport a subset of preferred pipes and the associated channel conditionreports. One advantage of this embodiment is that the base station hasthe freedom to schedule on any of the pipes and therefore can betterbalance the loads among the pipes. The disadvantage may be the need tofeedback more information.

In general, wireless terminals can employ a variety of mechanisms andformats to feed back their channel condition and characteristics. In oneembodiment each terminal can report a list of preferred pipes when itconnects with the base station. Later, the wireless terminal updates thebase station when its preferred pipes change. Such updates can occur inan asynchronous manner. In an alternative embodiment, each terminal canperiodically report to the base station a list of preferred pipes. Inaddition to the choice of the preferred pipe, the terminal also reportsthe channel quality estimate on the pipe (such as SNR) to the basestation. The frequency of reporting the channel condition can bedifferent from, and preferably faster than, that of reporting thepreferred pipes. Moreover, the format of the channel condition reportscan be different depending on the preferred pipes.

The advantages of this invention can be realized in multiuser systemsthat encompass a wide variety of devices. Wireless terminals thatfeature multiple antennas are in a position to realize MIMO channels incooperation with the multiple transmit antennas at the base station,especially if they experience a rich multipath structure in the wirelesschannels. If these devices are in a position to track the channel matrixof the channel response coefficients associated with each of thetransmit and receive antennas, a rich family of space-time codes can beused for data transmission. One or more of the pipes in the system canbe dedicated to provide service to such devices, which would indicatetheir capabilities and choice of pipe to the base station through acontrol channel. As an extension of this concept, one pipe can bededicated to transmit space-time codes that maximize spatialmultiplexing gain for mobiles whose channel conditions support it.Another pipe can be dedicated for space-time codes where the degrees offreedom are used to provide diversity instead of high data rates formobiles that may require it. Naturally, the mobiles may prefer not toselect a MIMO-optimized pipe if their wireless channels are unsuitable.

The invention is described in this document with a set of transmittechniques used in an illustrative manner. The invention applies equallywell to other multiple-antenna transmit techniques which may be used inindependent pipes as described in this document.

Thus far, the total power available on each pipe has not beenconsidered. Different embodiments of this invention could choose thetotal transmit power in different ways. One straightforward choice wouldresult in the total transmit power per degree of freedom being the samein each of the parallel pipes. Alternatively, the transmit powers can bedifferent on different pipes as illustrated in FIG. 12. Thisillustration is an embodiment of this invention where two adjoining basestations choose the transmit powers in such a manner that the cellboundaries are likely to different for different pipes. FIG. 12 includesa graph 1200 corresponding to base station 1 and a graph 1250corresponding to base station 2. Graph 1200 includes a vertical axis1202 representing frequency and a horizontal axis 1204 representing basestation 1 transmit power level. Block 1206 represents the base station 1transmit power for pipe A; block 1208 represents base station 1 transmitpower for pipe B; block 1210 represents base station 1 transmit powerfor pipe C. Graph 1250 includes a vertical axis 1252 representingfrequency and a horizontal axis 1254 representing base station 2transmit power level. Block 1256 represents the base station 2 transmitpower for pipe A; block 1258 represents base station 2 transmit powerfor pipe B; block 1260 represents base station 2 transmit power for pipeC. With regard to A pipes, block 1206 represents a high power level,while block 1256 represents an intermediate power level. With regard toB pipes, block 1208 represents an intermediate power level, while block1258 represents a low power level. With regard to pipe C, block 1210represents a low power level, while block 1260 represents a high powerlevel. Thus, a wireless terminal is likely to not be at a cell boundaryon each of the pipes simultaneously. This improves the capacity of thesystem. This power allocation is not necessarily static either. Thetotal transmit power can be varied at a slow rate for each of theparallel pipes. Power allocation also becomes important when a trafficsegment is transmitted across multiple pipes. The base station canallocate power differently across the pipes in accordance with therespective channel conditions on the pipes with respect to the wirelessterminal receiving the segment.

FIG. 13 illustrates an exemplary communications system 10 implemented inaccordance with the invention. In the system 10, multiple mobileterminals, shown as mobile nodes MN 1 (14) through MN N (16) communicatewith the base station 12 through the use of communication signals 13,15. Each mobile terminal may correspond to a different mobile user andare therefore sometimes referred to as user terminals. The signals 13,15 may be, e.g., OFDM signals. The signals 13, 15 may be transmittedusing one or more pipes between an MN and the base station 12. The basestation 12 and mobile stations 14, 15 each implement the method of thepresent invention. Thus, signals 13, 15 include various signals of thetypes discussed above, which are transmitted in accordance with theinvention.

FIG. 14 illustrates an exemplary access router, e.g., base station 12,implemented in accordance with the invention. The base station 12includes antennas 1403, 1405, 1407 and receiver transmitter circuitry1402, 1404. Multiple, e.g., two or more, transmit antennas 1405, 1407are used to facilitate beam forming and multiple transmit pipes withdifferent characteristics, to each pipe. The receiver circuitry 1402includes a decoder 1433 while the transmitter circuitry 1404 includes anencoder 1435. The circuitry 1402, 1404 is coupled by a bus 1430 to anI/O interface 1408, processor (e.g., CPU) 1406 and memory 1410. The I/Ointerface 1408 couples the base station 12 to the Internet and to othernetwork nodes. The memory 1410 includes routines, which when executed bythe processor 1406, cause the base station 12 to operate in accordancewith the invention. Memory includes communications routines 1423 usedfor controlling the base station 12 to perform various communicationsoperations and implement various communications protocols. The memory1410 also includes a base station control routine 1425 used to controlthe base station 12 to implement the steps of the method of the presentinvention described above in the sections which discuss, e.g., a basestation or an access router, operation and signaling. The base stationcontrol routine 1425 includes a scheduling module 1426 used to controltransmission scheduling and/or communication resource allocation.Transmission scheduling is based in various embodiments, on informationabout channel characteristics on different pipes received from one ormore mobile nodes. Thus, module 1426 may serve as a scheduler. Memory1410 also includes information used by communications routines 1423, andcontrol routine 1425. The information 1412 includes an entry for eachactive mobile station user 1413, 1413′ which lists the active sessionsbeing conducted by the user and includes information identifying themobile station (MT) being used by a user to conduct the sessions.

FIG. 15 illustrates an exemplary mobile node 14 implemented inaccordance with the present invention. The mobile node 14 may be used asa mobile terminal (MT). The mobile node 14 includes receiver andtransmitter antennas 1503, 1505, 1507 which are coupled to receiver andtransmitter circuitry 1502, 1504 respectively. Multiple transmitterantennas 1505, 1507 are used to support beamforming and multipletransmit pipes to a BS with different characteristics. The receivercircuitry 1502 includes a decoder 1533 while the transmitter circuitry1504 includes an encoder 1535. The receiver transmitter circuits 1502,1504 are coupled by a bus 1509 to a memory 1510. Processor 1506, undercontrol of one or more routines stored in memory 1510 causes the mobilenode to operate in accordance with the methods of the present inventionas described above. In order to control mobile node operation memoryincludes communications routine 1523, and mobile node control routine1525. The mobile node control routine 1525 is responsible for insuringthat the mobile node operates in accordance with the methods of thepresent invention and performs the steps described above in regard tomobile node operations. The memory 1510 also includesuser/device/session/resource information 1512 which may be accessed andused to implement the methods of the present invention and/or datastructures used to implement the invention.

FIG. 16 is an illustration of an exemplary wireless communicationssystem 1600, implemented in accordance with the present invention.Exemplary wireless communications system 1600 includes a plurality ofbase stations (BSs): base station 1 1602, base station M 1614. Cell 11604 is the wireless coverage area for base station 1 1602. BS 1 1602communicates with a plurality of wireless terminals (WTs): WT(1) 1606,WT(N) 1608 located within cell 1 1604. WT(1) 1606, WT(N) 1608 arecoupled to BS 1 1602 via wireless links 1610, 1612, respectively.Similarly, Cell M 1616 is the wireless coverage area for base station M1614. BS M 1614 communicates with a plurality of wireless terminals(WTs): WT(1′) 1618, WT(N′) 1620 located within cell M 1616. WT(1′) 1618,WT(N′) 1620 are coupled to BS M 1614 via wireless links 1622, 1624,respectively. WTs (1606, 1608, 1618, 1620) may be mobile and/orstationary wireless communication devices. Mobile WTs, sometimesreferred to as mobile nodes (MNs), may move throughout the system 1600and may communicate with the base station corresponding to the cell inwhich they are located. Region 1634 is a boundary region between cell 11604 and cell M 1616.

Network node 1626 is coupled to BS 1 1602 and BS M 1614 via networklinks 1628, 1630, respectively. Network node 1626 is also coupled toother network nodes/Internet via network link 1632. Network links 1628,1630, 1632 may be, e.g., fiber optic links. Network node 1626, e.g., arouter node, provides connectivity for WTs, e.g., WT(1) 1606 to othernodes, e.g., other base stations, AAA server nodes, home agent nodes,communication peers, WT(N′), 1620, etc., located outside its currentlylocated cell, e.g., cell 1 1604.

FIG. 17 illustrates an exemplary base station 1700, implemented inaccordance with the present invention. Exemplary BS 1700 may be a moredetailed representation of any of the BSs, BS 1 1602, BS M 1614 of FIG.16, BS 1700 includes a receiver 1702, a transmitter 1704, a processor,e.g., CPU, 1706, an I/O interface 1708, I/O devices 1710, and a memory1712 coupled together via a bus 1714 over which the various elements mayinterchange data and information. In addition, the base station 1700includes a receiver antenna 1 1715 which is coupled to the receiver1702. In some embodiments, e.g., a MIMO embodiment, base station 1700includes additional receiver antenna(s), receiver antenna a 1717 coupledto receiver 1702. The base station 1700, as shown in FIG. 3, alsoincludes multiple transmitter antennas, (antenna 1 1718, antenna n 1722)coupled to transmitter 1704. Transmitter antennas 1718, 1722 are usedfor transmitting information, e.g., downlink traffic channelinformation, independent pilot signals on each pipe, and/or assignmentinformation from BS 1700 to WTs 1800 (see FIG. 18) while receiverantenna(s) 1715, 1717 is used for receiving information, e.g., channelcondition feedback information, pipe selection information, and/or pipecontrol information, as well as data, from WTs 1800.

The memory 1712 includes routines 1724 and data/information 1726. Theprocessor 1706 executes the routines 1724 and uses the data/information1726 stored in memory 1712 to control the overall operation of the basestation 1700 and implement the methods of the present invention. I/Odevices 1710, e.g., displays, printers, keyboards, etc., display systeminformation to a base station administrator and receive control and/ormanagement input from the administrator. I/O interface 1708 couples thebase station 1700 to a computer network, other network nodes, other basestations 1700, and/or the Internet. Thus, via I/O interface 1708 basestations 1700 may exchange customer information and other data as wellas synchronize the transmission of signals to WTs 1700 if desired. Inaddition I/O interface 1708 provides a high speed connection to theInternet allowing WT 1800 users to receive and/or transmit informationover the Internet via the base station 1700.

Receiver 1702 includes a decoder 1703. Receiver 1702 uses decoder 1703to processes signals received via receiver antenna(s) 1715, 1717 andextracts from the received signals the information content includedtherein. The extracted information, e.g., data, channel conditionfeedback information for each pipe, pipe selection, and/or pipe controlinformation, is communicated to the processor 1706 and stored in memory1712 via bus 1714.

Transmitter 1704 includes an encoder 1705 which encodesdata/information, e.g., blocks of downlink traffic channeldata/information, prior to transmission. Transmitter 1704 transmitsinformation, e.g., data, assignment information, and/or pilot signals oneach pipe to WTs 1800 via multiple antennas, e.g., antennas 1718, 1722.Transmitter 1704 includes a plurality of phase/amplitude controlmodules, phase/amplitude control module 1 1716, phase/amplitude controlmodule n 1720. In the illustrated example of FIG. 17, a separatephase/amplitude control module, (1716, 1720) is associated with each ofthe transmit antennas (1718, 1722), respectively. The antennas 1718,1722 at the BS 1700 are spaced far enough apart so that the signals fromthe antennas 1718, 1722 go through statistically independent paths, andthus the channels the signals go through are independent of each other.The distance between antennas 1718, 1722 is a function of the anglespread of the WTs 1800, the frequency of transmission, scatteringenvironment, etc. In general, half a wavelength separation betweenantennas, based on the transmission frequency, is usually the sufficientminimum separation distance between antennas, in accordance with theinvention. Accordingly, in various embodiments, antennas 1718, 1722 areseparated by one half a wavelength or more, where a wavelength isdetermined by the carrier frequency f_(k) of the signal beingtransmitted.

The phase and amplitude control modules 1716, 1720 perform signalmodulation and control the phase and/or amplitude of the signal to betransmitted under control of the processor 1706. Phase/amplitude controlmodules 1716, 1720 introduce amplitude and/or phase variations into atleast one of a plurality, e.g., two, signals being transmitted to a WT1800 to thereby create a variation, e.g., an amplitude variation overtime, in the composite signal received by the WT 1800 to whichinformation is transmitted from multiple antennas 1718, 1722. Thecontrol modules 1716, 1720 are also capable of varying the datatransmission rate, under control of the processor 1706, as a function ofchannel conditions and/or channel selection in accordance with thepresent invention. In some embodiments, phase/amplitude control modules1716, 1720 change phase and/or amplitude by changing coefficients.

As mentioned above, the processor 1706 controls the operation of thebase station 1700 under direction of routines 1724 stored in memory1712. Routines 1724 include communications routines 1728, and basestation control routines 1730. The base station control routines 1730include a transmit scheduler module 1732, a pilot signals generation andtransmission module 1734, a WT channel pipe selection/channel qualityreport processing module 1736, a switched opportunistic beamformingmodule 1738, a Alamouti control module 1740, a pipe power allocationmodule 1742, and a pipe control modification module 1744.

Data/Information 1726 includes segment data/information 1746, aplurality of wireless terminal (WT) data/information 1748, and pipeinformation 1752. WT data/information 1748 includes WT 1 information1749 and WT N information 1750. Each WT information set, e.g., WT 1information 1749 includes data 1758, terminal ID information 1760,high/low mobility user classification information 1762, pipeselection/channel condition information 1764, pipe control informationfrom WT 1766, assigned pipe information 1768, and assigned segmentinformation 1770.

Segment data/information 1746 includes data, e.g., user data, intendedto be transmitted on downlink traffic segments to WTs 1800, locatedwithin the cell of BS 1700, and user data received on uplink trafficsegments from WTs 1800. Data 1758 includes user data associated with WT1, e.g., data received from WT 1 intended to be forwarded to acommunication peer, e.g., WT N, and data receiver from a peer of WT 1,e.g., WT N, intended to be forwarded to WT 1. Terminal ID information1760 includes a current base station assigned identity for WT 1.High/low mobility user classification information 1762 includes aclassification of WT 1 as a high or low mobility user. In someembodiments, pipes, e.g., communication channels and/or segments may bedivided and assigned by categories corresponding to a user's mobilityclassification. Pipe selection/channel condition information 1764includes information from a WT feedback report indicating the WT'sselected pipe(s), e.g., communication channel(s), and correspondingchannel quality information, e.g., SNR, SIR, fading information, etc.Pipe control information from WT 1766 includes information from the WT1800 instructing the BS 1700 to alter the selected pipe based on WTpreferences. Assigned pipe information 1768 includes informationidentifying the specific pipe from a plurality of pipes which BS 1700has assigned to WT 1800, e.g., for downlink traffic. Assigned pipeinformation 1768 also includes characteristics of the pipe, e.g.,bandwidth, tones, data rate, modulation scheme, and/or any uniquecharacteristic of the pipe incorporated due to the pipe controlinformation communicated by the WT. Assigned segment information 1770includes information identifying the segments assigned to the WT, e.g.,the segments in the assigned pipe. In some embodiments, the WT shallrequest and be assigned specific segments, for downlink traffic channelinformation.

Pipe information 1752 includes a plurality of pipe information, pipe 1information 1754, pipe N information 1756. Each pipe information set,e.g., pipe 1 information 1754 includes transmission techniqueinformation 1772, tone information 1774, pilot information 1776, andantenna information 1778. Transmission technique information includesinformation pertaining to the type of transmission technique(s) and/ortechnology selected for the pipe, e.g., OFDM, CDMA, an opportunisticbeamforming technique, an Alamouti technique, etc. Tone information 1774includes the bandwidth and/or set of tones allocated to the pipe as wellas any tone hopping information relevant to the pipe. Pilot information1776 includes information defining pilot signals to be generated for thepipe. By having independent pilot signals transmitted for each pipe, theWT can measure and estimate the channel quality for each pipe. Antennainformation 1778 includes information indicating which correspondingantennas 1718, 1722 should be used for which signals componentstransmitted for the pipe.

Communications routines 1728 control the transmission and reception ofdata by transmitter 1704 and receiver 1702, respectively. Communicationsroutines 1728 also implement various communications protocols used by BS1700. Communications routines 1728 are also responsible for controllingthe display and/or audio presentation of received information via I/Odevices 1710.

Base station control routines 1730 control the operation of the basestation 1700 and implement the methods of the present invention.Scheduler module 1732 schedules users, e.g., WTs to segments, e.g.,downlink traffic segments, on assigned pipes, e.g., in response toselected pipe requests from the WTs. Pilot signals generation andtransmission module 1734 generates and transmits pilot signals for eachof the potential downlink pipes which may be assigned, thus allowing WTsto measure and evaluate independent channel estimates for each potentialpipe. WT channel pipe selection/channel quality report processing module1736 receives WT feedback reports including the WTs selected (preferred)pipe and associated channel quality report information, e.g., SNR, SIR,fading information. In some embodiments, the BS 1700 may receiveinformation on a list of pipes that are acceptable to the WT. In someembodiments, the WTs may indicate specific requested segments fortransmission. Module 1736 processes the received feedback informationand makes decisions regarding pipe assignment between the various WTsrequesting resources. The assignment decisions may be conveyed to theWTs in assignments segments. The switched opportunistic beamformingmodule 1738 is used in controlling the transmitter to performopportunistic beamforming in designated pipes. Alamouti control module1740 is used to control the transmitter perform Alamouti diversitytechniques on designated pipes. Pipe power allocation routine 1742 isused to control the power levels assigned to each pipe. Pipe controlmodification module 1744 uses pipe control information from WT 1766, toalter pipes for specific wireless terminals, e.g., to customize a pipebased on the WT preferences communicated in information 1766.

FIG. 18 illustrates an exemplary wireless terminal 1800, implemented inaccordance with the present invention. Exemplary wireless terminal 1800may be a more detailed representation of any of the WTs 1606, 1608,1618, 1620 of exemplary system wireless communication system 1600 ofFIG. 16. WT 1800 includes a receiver 1802, a transmitter 1804, I/Odevices 1806, a processor, e.g., a CPU, 1808, and a memory 1810 coupledtogether via bus 1812 over which the various elements may interchangedata and information. Receiver 1802 is coupled to antenna 1814. In someembodiments, e.g., MIMO embodiments, the receiver is coupled toadditional antenna(s), antenna N 1815. Transmitter 1804 is coupled toantenna 1816. In some embodiments, e.g., using multiple uplink parallelpipes, multiple additional antenna(s), antenna N 1817, may be coupled totransmitter 1804. In some embodiments, a single antenna may be used inplace of the two individual antennas 1814 and 1816.

Receiver 1802 includes a decoder 1803. Downlink signals transmitted fromBS 1700 are received through antenna 1814 and/or 1815 and processed byreceiver 1802 including decoding by decoder 1803 and recovery of userdata. Transmitter 1804 includes an encoder 1805, which encodes userinformation prior to transmission. Transmitter 1804 transmits uplinksignals through antenna 1816 and/or 1817 to BS 1700. Uplink signalsinclude uplink traffic channel data/information, a selected downlinkpipe, downlink pipe feedback channel estimation information for theassociated selected pipe and/or for alternate pipes, and/or controlinformation including instructions to the BS 1700 to alter the selectedpipe or to form a pipe, e.g., through reallocation of resources, basedon WT preferences, in accordance with the invention. I/O devices 1806include user interface devices such as, e.g., microphones, speakers,video cameras, video displays, keyboard, printers, data terminaldisplays, etc. I/O devices 1806 may be used to interface with theoperator of WT 1800, e.g., to allow the operator to enter user data,voice, and/or video directed to a peer node and allow the operator toview user data, voice, and/or video communicated from a peer node, e.g.,another WT 1800.

Memory 1810 includes routines 1818 and data/information 1820. Processor1806 executes the routines 1818 and uses the data/information 1820 inmemory 1810 to control the basic operation of the WT 1800 and toimplement the methods of the present invention. Routines 1818 includecommunications routine 1822 and WT control routines 1824. WT controlroutines 1824 include a channel condition measurement module 1826, apipe selection module 1828, a pipe selection/segment selection/channelcondition reporting module 1830, and a pipe control informationselection and reporting module 1832.

rata/Information 1820 includes segment data/information 1834, basestation information 1836, and user information 1838. Segmentdata/information 1834 includes user data, e.g., data/information to betransmitted to BS 1700 intended for a peer node in a communicationsession with WT 1800, downlink channel feedback information on thepipes, a selected downlink pipe(s), and/or selected pipe controlinformation.

Base station information 1836 includes a plurality of sets ofinformation, base station 1 information 1840, base station N information1842. Base station information 1836 includes information specific toeach base station, e.g., slope values that may be used in hoppingsequences, carrier frequencies used by different base stations,modulation methods used by different base stations, beamformingvariations that are base station dependent, division of available airlink resources into pipes, e.g., channels, technologies used bydifferent pipes. BS 1 info 1840 includes base station identificationinformation 1844, and a plurality of base station pipe information sets,pipe 1 information 1846, pipe N information 1848. Pipe 1 information1846 includes transmission technique information 1850, tone information1852, pilot information 1854, and antenna information 1856. Base stationID information, e.g., a value of slope in an tone hopping sequenceassigned to a particular BS 1700 in an OFDM system, allows the WT 1800to identify the particular BS 1700 to which it is communicating.Transmission technique information 1850 includes information pertainingto the type of transmission technique(s) and/or technology for the pipe,e.g., OFDM, CDMA, an opportunistic beamforming technique, an Alamoutitechnique, etc. Tone information 1852 includes the bandwidth and/or setof tones allocated to the pipe as well as any tone hopping informationrelevant to the pipe. Pilot information 1854 includes informationdefining pilot signals to be received for the pipe. By having BS 1700transmit pilot signals for each pipe, the WT 1800 can measure andestimate the channel quality independently for each pipe. Antennainformation 1856 includes information indicating which correspondingantennas 1814, 1815 should be used for which signals components receivedfor the pipe.

User information 1838 includes base station identification information1858, terminal ID information 1860, assigned channel information 1862,high/low mobility user classification information 1864, a plurality ofpipe measurement/channel quality estimation information (pipe 1measurement/channel quality estimate information 1866, pipe Nmeasurement/channel quality estimate information 1868), selectedpipe/segment information 1870, selected pipe/selected segment/channelquality report information 1872, and selected pipe control information1874.

User information 1838 includes information being currently used by WT1800. Base station ID information 1858 includes identificationinformation of the base station in whose cell WT 1800 is currentlylocated, e.g., a value of slope used in a hopping sequence. Terminal IDinformation 1860 is a base station assigned ID used for currentidentification of WT 1800 by the BS 1700 in whose cell WT 1800 islocated.

Assigned channel information 1862 includes downlink channel(s) assignedby the BS 1700 for the WT 1800 to expect user data to be transmitted on.Assigned channel information 1862 includes information identifying thespecific pipe from a plurality of pipes which BS 1700 has assigned to WT1800, e.g., for downlink traffic. Assigned channel information 1800 alsoincludes characteristics of the pipe, e.g., bandwidth, tones, data rate,modulation scheme, and/or any unique characteristic of the pipeincorporated due to the pipe control information communicated by the WT1800. Assigned channel information 1862 also includes informationidentifying the segments assigned to the WT 1800, e.g., the segments inthe assigned pipe.

High/low mobility user classification information 1864 includes aclassification of WT 1800 as a high or low mobility user. In someembodiments, pipes, e.g. communication channels and/or segments may bedivided and assigned by categories corresponding to a user's mobilityclassification. Pipe 1 measurement/channel quality estimate information1866 includes measurement information, e.g., received pilot signalmeasurement information, and estimation information corresponding topipe 1, e.g., communication channel 1. Such information 1866 includeschannel quality information, e.g., SNR, SIR, fading information, etc,corresponding to pipe 1. Pipe N measurement/channel quality estimateinformation 1868 includes measurement and estimation information similarto information set 1866 but corresponding to pipe N, e.g., communicationchannel N. Selected pipe/segment information 1870 includes a. WT 1800pipe selection and/or segment selections which are communicated to BS1700. Selected pipe/selected segment/channel quality report information1872 includes channel quality information, e.g., information derivedfrom information sets 1866, 1868, corresponding to the WT selected pipedesignated in information 1870, that shall be included in a feedbackreport to BS 1700. Selected pipe control information 1874 includescontrol information that shall be sent from the WT 1800 to BS 1700instructing the BS 1700 to alter the selected pipe or to form a pipe,through reallocation of resources, based on WT 1800 preferences. In someembodiments, the WT shall request and be assigned specific segments,e.g., for downlink traffic channel information.

The communications routine 1822 controls the transmission and receptionof data by transmitter 1804 and receiver 1802, respectively.Communications routine 1822 also implements the various communicationsprotocols used by the WT 1800. Communications routine 1822 is responsiveto scheduling information, received from BS 1700 to insure that uplinktransmission data/information is transmitted by the WT 1800 at the timesauthorized by the BS 1700 and that downlink transmissiondata/information is received by WT 1800 at the appropriate times.Communications routines 1822 are also responsible for controlling thedisplay and/or audio presentation of received information from BS 1700to a user via I/O devices 1806.

WT control routines 1824 control the operation of the WT 1800 andimplement methods of the present invention. Channel conditionmeasurement module 1826 measures and estimates channel conditions for aplurality of pipes, e.g., channels, obtaining pipe 1 measurement/channelquality estimate information 1866, pipe N measurement channel qualityestimate information 1868.

Pipe selection module 1828 compares channel measurement and/orestimation information, e.g., pipe 1 measurement/channel qualityestimate information 1866, pipe N measurement/channel quality estimateinformation 1868, selects a channel, e.g., the channel with the bestquality estimate, and stores the selection in selected pipe/segment info1870. In some embodiments, the pipe selection module 1828 may selectmore than one pipe which may be used, e.g., a subset of pipes which havea quality level sufficient to support the needs of WT 1800. In someembodiments, the pipe selection module 1828 selects specific segments,e.g., specific downlink traffic segments, that WT 1800 would like to beBS 1700 to assign WT 1800.

Pipe selection/segment selection/channel condition reporting module 1830uses data information 1820 including the selected pipe/segment info 1870and the corresponding measurement/quality estimate information from info1866, 1868 to generate a selected pipe/selected segment/channel qualityreport 1872. The reporting module 1830 in conjunction with thecommunications routine 1822 controls the transmitter 1804 to transmitthe report information 1872 to the BS 1700.

Pipe control information selection and reporting module 1832 uses thedata/information 1820 including high/low mobility user classificationinformation 1864, selected pipe/segment information 1870, thecharacteristics of the selected pipe included in pipe info 1846, 1848,and/or characteristics of the segment data/information 1834, e.g.,voice, data, video, data rate, etc., to generate selected pipe controlinformation 1874. Pipe control information selection and reportingmodule 1832 in conjunction with the communications routine 1822communicates the selected pipe control information 1874 to the BS 1700.In some embodiments, selected pipe, selected pipe channel qualityfeedback information and selected pipe control information arecommunicated in the same report to the BS 1700. In some embodiments,some of the set of selected channel, channel quality information, andselected pipe control information is communicated and used by the BS1700, e.g., one of the three items, while the other information is not.

FIG. 19 is a flowchart 1900 illustrating an exemplary communicationsmethod in accordance with the present invention. Operation starts instep 1902 where the communications system is powered on and initialized.In step 1904 a base station is operated to generate and transmitsignals, e.g., pilot signals, for each of a plurality of differentwireless communications channels, which the base station can use tocommunicate information between the base station and a wirelesscommunications terminal, said plurality of different wirelesscommunications channels including at least a first communicationschannel and a second communications channel, the first and the secondcommunications channels having different quality characteristics whichare a function of first and second transmission technologies used toestablish said communications channels, said first and secondtechnologies being different. In some embodiments, the first and secondtechnologies are different access technologies, e.g., differentincompatible access technologies. In some embodiments, the differentaccess technologies include at least two of the following technologies:CDMA, OFDM, and single carrier technology. In some embodiments, thedifferent access technologies include frequency hopping technologies andnon-frequency hopping technologies. In some embodiments, the differentaccess technologies include different technologies defined on differenttechnology standards which are incompatible as indicated by neither ofthe two standards complying to the other. Operation proceeds from step1904 to step 1906.

In step 1906, the wireless communications terminal is operated toreceive and process signals, e.g., pilot signals, for each of theplurality of different communications channels generating qualityinformation for each of the plurality of different communicationschannels. Operation proceeds from step 1906 to step 1908. In step 1908,the wireless communications terminal is operated to use the generatedquality information to maintain a set of communications qualityinformation for the plurality of different wireless communicationschannels. Then, in step 1910, the wireless communications terminal isoperated to select between the plurality of different communicationschannels based on the maintained set of communications qualityinformation to thereby select the channel corresponding to thetransmission technology which provides the better transmissioncharacteristics to said wireless communication terminal. Next, in step1912, the wireless communications terminal is operated to communicatethe channel selection to the base station. In step 1914, the wirelesscommunications terminal is operated to communicate channel qualityinformation, e.g., SNRs, SIRS, fading information, etc., associated withthe selected channel and with alternative channel(s) to the basestation. Operation proceeds from step 1914 via connecting node A 1916 tostep 1918. In step 1918, the wireless communications terminal isoperated to communicate channel control information associated with theselected channel to the base station, e.g., a bandwidth, a duration, atechnology type, etc. In some embodiments, the information communicatedin steps 1912, 1914, and 1918 is communicated together in a signal,e.g., message. In some embodiments some of the information of steps1912, 1914, and 1918 is not communicated to the base station, e.g., thewireless communication device transmits information from one of thethree steps 1912, 1914, 1918, and does not transmit informationcorresponding to the other two steps. Operation proceeds from step 1918to step 1920.

In step 1920, the base station is operated to receive the communicatedselected channel, the communicated channel quality information, and thecommunicated channel control information. Then in step 1922, the basestation is operated to reallocate communications resources from one ofthe plurality of communications channels to a generated communicationschannel using a different technology as a function of the receivedinformation, e.g., selected channel, channel quality information, and/orchannel control information, from the wireless communications terminal.Operation proceeds from step 1922 to step 1924. In step 1924, the basestation is operated to assign the generated communications channel tothe wireless communication terminal and communicate the assignmentinformation to the wireless communications terminal. Then, in step 1926,the wireless communications terminal is operated to receive theassignment from the base station. In step 1928, the base station isoperated to transmit user data/information, e.g., downlink trafficchannel user data/information, on the assigned generated communicationschannel. Then, in step 1930, the wireless communications terminal isoperated to receive and process user data/information downlink trafficchannel user data/information, on the assigned generated communicationschannel. Operation proceeds from step 1930 to end node 1932.

FIG. 20 illustrates a flow chart 2000 showing the steps involved withthe operation of a wireless terminal, e.g., exemplary mobile node, inaccordance with the present invention. As shown in FIG. 20. The stepsshown in FIG. 20 may be performed by a wireless terminal operating undersoftware control where the software is implemented in accordance withthe present invention and executed by the wireless terminals CPU. Theroutine starts in step 2002 when the control software is executed, e.g.,upon wireless terminal activation or power up. Operation proceeds fromstart step to steps 2004 and 2008 which represent the start of parallelprocessing paths. The motion estimation path which starts in step 2008is optional and not employed in some embodiments.

In step 2008 the wireless terminal determines, e.g., estimates, the rateof wireless terminal motion form one or more received signals. Thereceived signals may be GPS position information signals, signalsreceived from the base station instructing the wireless terminal toadvance or delay its clock, e.g., as part of a symbol transmissiontiming adjustment, power control signals or other signals. Rate ofmotion may also be determined by measuring a Doppler shift in a signalreceived from the base station. With the rate of motion determined instep 2008, operation proceeds to step 2010 where the rate of motion isexamined to determine if it is a fast or slow rate of motion. Other ratedeterminations are also possible. Form step 2010 operation proceeds tostep 2012 or 2014 which involve selecting a technology to be used forcommunication to match the rate of motion. Step 2012 involves selectionof a technology which is well suited for wireless terminals movingquickly. The method selected in step 2012 in some embodiments usesrelatively little or no channel information to adjust BS antennapatterns and/or other base station transmission characteristics. TheAlamoti communications method is one example of a communicationstechnology which may be selected in step 2012 while other selections arealso possible. Operation proceeds from step 2012 to step 2016.

In step 2014, which corresponds to a slow rate of motion, e.g., a rateof motion which is slower than the rate threshold value used in step2010, a technology which is well suited for a slow moving or stationarywireless terminal is selected. The selected transmission or accesstechnology selected in step 2012 uses channel feedback information fromthe mobile to adjust the antenna patterns and/or other transmissioncharacteristics. The technology will, in many cases, involve the use ofa higher channel feedback rate than is used for the technology whichwill be selected in step 2012. Thus, in accordance with the presentinvention, the selected technology in the case of a slow moving mobilemay, and often does, involve more channel condition feedbackinformation, e.g., SNR or SIR, reports, to the base station than areprovided by the wireless terminal in the case of a fast moving wirelessterminal where the channel conditions change rapidly. Operation proceedsfrom step 2014 to step 2016.

In the processing path starting with step 2004, channel qualityestimates generated for multiple channels, e.g., channels correspondingto different and often incompatible communications technologies. In step2004 channel quality estimates are generated for at least 2 channelscorresponding to different communications technologies. Then, in step2006 the channel quality information maintained in the wirelessterminals memory for each of a plurality of different channelscorresponding to different communications technologies is updated withat least the information generated in step 2004. Operation proceeds fromstep 2006 to step 20016.

In step 2016 the communications channel which the wireless terminalwould prefer to use is selected based on the channel qualityinformation, for example, the communications channel having the bestchannel quality is selected. This selection may be subject to thetechnology selection made in step 20012, 20014 and may therefore bebased on the wireless terminal's rate of motion. In some embodimentsmotion rate information is not used in step 2016 in which case thewireless terminal will simply select the best channel as indicated bythe sets of channel quality information maintained for each of theplurality of channels which are supported by the base station.

Operation proceeds from channel selection step 2016 to communicationstep 2018. Selection step 2016 may be skipped, e.g., omitted, inembodiments where the base station is responsible for channel selection.In such embodiments operation would proceed directly from steps 2006,and/or 20012, 2014 to step 2018. In step 2018 the wireless terminalcommunications a channel selection if a channel selection was made. Thesignal indicating a selected channel was generated from informationindicating the channel quality of at least two different channels as aresult of the selection process performed in step 2016. In additionand/or as an alternative to indicating a channel selection, the wirelessterminal may generate and transmit to the base station one or moresignals providing channel quality information for multiple channels, atleast two channels corresponding to different technologies, and/ortechnology selection information, e.g., information indicating aselected transmission technology. In response to such signals the basestation will normally assign one or more segment of a selected channelto the wireless terminal and/or make a channel selection based on thereceived information. The base station may, and in some embodimentsdoes, create a channel corresponding to the selected technology and/orreallocate resources from a different channel to a channel correspondingto the selected technology and/or selected channel. The resources whichare reallocated in response to wireless terminal signals will normallycome from a channel implemented using a technology which the wirelessterminal has not selected. In this manner additional channel capacitymay be dynamically established in response to a wireless terminalsselection or need to use a channel implemented using a particulartechnology. In step 2018 the wireless terminal may also signal to thebase station the amount of data it seeks to send on a channelcorresponding to a particular technology and/or the period of time itseeks to use a channel corresponding to a particular technology.

Operation proceeds from communication/signal transmission step 2018 tostep 2020 in which the wireless terminal switches to the selectedchannel if it is different from a previously selected channel. If thetechnology used in the selected communications channel is different formthe previously used channel, the wireless terminal changes theprocessing of received signals and/or one or more physical receptioncharacteristics such as the number of antennas used to receive signalscommunicated in the channel as may be necessary to receive and processsignals in accordance with the technology used to implement the selectedchannel. Wireless terminal operation while in an on-state occurs on anongoing basis with operation proceeding form step 2020 to steps 1004and/or 2008. In this manner, the channels will be periodically evaluatedand a different channel corresponding to a different technology may beselected as the wireless terminals conditions and/or rate of movementvary.

FIG. 21 illustrates the steps of a method 2100 preformed by a basestation in one exemplary embodiment. The method begins in step 2102.Operation proceeds from step 2102 to step 2103. In step 2103, the basestation receives at least one signal from a wireless terminal. Thesignal may be a channel selection signal indicating a selected wirelessterminal channel selection and request for an assignment of segments inthe selected channel. It might also be a signal indicating the qualityof multiple different channels as measured by the wireless terminalindicating a request for the BS to select a channel for the wirelessterminal and assign segment to the wireless terminal from the selectedchannel. Step 2103 is preformed on an ongoing bases with operationproceeding from step 2103 as signals are received. Once a signal isreceived form wireless terminal relating to a channel selection and/orassignment request, operation proceeds to steps 2108 and 2120. Step 2108represents the start of a processing path which is responsible formobile node motion detection and for selecting a transmission technologysuitable for the wireless terminals determined rate of motion. Steps2108, 2110, 2112, 2114 and channel selection step 2116 are similar tothose steps 2008, 2010, 2012, 2014 and channel selection step 2016previously described with regard to FIG. 20 but they occur in the basestation instead of the wireless terminal. Accordingly, these steps willnot be described in detail for the sake of brevity.

In step 2120 a determination is made if the received signal indicates aselected channel, e.g., a channel corresponding to a particulartransmission technology. If the signal does not indicate a selectedchannel, a operation proceeds to step 2116 where channel is selected,e.g., based on channel quality information in the received signal.Operation proceeds from 2120 in the case where the signal indicates aselected channel or from step 2116 where the base station selects thechannel to step 2122. In step 2122, a determination is made as towhether there are sufficient channel resources, e.g., available segmentsin the selected channel, to satisfy the request for the selectedchannel. If there are sufficient channel segments available in a channelimplemented with the technology corresponding to the requested channeltype, operation proceeds to step 2128. Otherwise operation proceeds fromstep 2122 to step 2124.

In step 2124 the base station reallocates communications resources tocreate and/or enlarge a channel corresponding to the technology of theselected channel in order to satisfy the wireless terminals request fora channel implemented with a specific technology. Operation thenproceeds to step 2128. In step 2128, the base station allocates segmentsin a channel implemented using the technology corresponding to theselected channel. Thus, the selected channel may be a channel created,e.g., in response to a wireless terminal's selection of a channelcorresponding to a particular technology, or a pre-existing channel.

Processing of signals from wireless terminals and channel segmentallocation and reallocations of channel resource occur on an ongoingbasis, e.g., while the base station is in operation.

Numerous various on the method of the present invention are possible.Different implementations can be achieved by using differentcombinations of steps and/or performing different processing orselection operations in a particular step.

A first exemplary communications method which will node be describedincludes a combination which involves performing the following step:

operating a wireless communications terminal to maintain a set ofcommunications quality information for a plurality of different wirelesscommunications channels which can be used to communicate informationbetween a base station and said wireless communications terminal, saidplurality of different wireless communications channels including atleast a first communications channel and a second communicationschannel, the first and second communications channels having differentquality characteristics which are a function of first and secondtransmission technologies used to establish said first and secondcommunications channels, respectively, said first and secondtransmission technologies being different;

operating the wireless terminal to generate a signal as a function ofthe maintained communications channel quality information correspondingto at least said first and said second communications channels; and

transmitting said signal to said base station.

In the first exemplary embodiment noted above, said signal may provideinformation on the quality of at least said first and said secondcommunications channel. The first exemplary method may further includethe step of operating the base station to select between multiple onesof said plurality of communications channels to use to communicateinformation to said wireless communications terminal as a function ofthe channel quality information included in said signal. Said first andsecond technologies used to implement the first exemplary method may be,and sometimes are, different incompatible access technologies. Thedifferent access technologies supported by a base station implementingthe method may and sometimes do include CDMA, OFDM, and narrowbandsignal carrier technologies. In some embodiments each of the differentaccess technologies corresponds to a different technology standard whichdefines requirements for complying with the particular accesstechnology, said different access technologies being incompatible asindicated by the technology standard corresponding to one of saiddifferent access technologies defining communications requirements whichviolate the defined requirements of the other different accesstechnologies.

In some embodiments of the first exemplary method at least one of thebase station and the wireless terminal includes multiple antennas whilethe method further includes the steps of: making a measurementindicative of a rate of motion of said wireless terminal and operatingone of the base station and mobile to select a communications channelfor use in communicating to said wireless terminal as a function of themeasurement indicative of the rate of motion of said mobile node. Eitherthe wireless terminal or the base station may make the measurementindicative of the rate of motion of the wireless terminal depending onthe particular implementation.

In some embodiments of the first method, the step of operating one ofthe base station and mobile to select a communications channel includesoperating said one to perform the steps of: selecting the firstcommunications technology when said measurement indicates a first rateof wireless terminal movement, said first communications technologyproviding a first amount of frequency diversity to the wirelessterminal; and selecting a communications channel corresponding to thesecond communications technology when said measurement indicates asecond rate of wireless terminal movement, the second communicationstechnology using antenna beam forming as a function of feedbackinformation received from the wireless terminal, said second rate ofwireless terminal movement being slower than said first rate of wirelessterminal movement. In various embodiments of the first exemplary methodwhich involve making a measurement indicative of a rate of motion ofsaid wireless terminal the step of making a measurement may includemaking a measurement of a Doppler shift in a signal transmitted betweensaid base station and said wireless terminal. The step of making ameasurement indicative of a rate of motion of said wireless terminal mayalternatively include measuring the rate of change in at least one of:timing control signals which are used to instruct the mobile to make atclock timing change; the rate at which the power in a periodicallytransmitted signal from the mobile node changes over with time, a rateof change in a measured quality of a communications channel, and a rateof change in a channel fading measurement. In the exemplary method, thestep of operating one of the base station and mobile to select acommunications channel may and sometimes does include: selecting thefirst communications channel corresponding to a first technology whensaid measurement indicates a first rate of wireless terminal movement,said first communications technology using a first amount of channelquality feedback signaling from said wireless terminal to said basestation; and selecting a communications channel corresponding to thesecond communications technology when said measurement indicates asecond rate of wireless terminal movement, the second rate of wirelessterminal movement being lower than said first rate of wireless terminalmovement, the second communications technology using a second amount ofchannel feedback information, the second amount of channel feedbackinformation being greater than said first amount of channel qualityfeedback information. In some embodiments, said first communicationstechnology uses two fixed antennas and is a technology which used anAlamouti transmission method, said first communications technology usingzero channel quality feedback signaling to said base station to controlthe antenna pattern used to transmit signals from said base station inparticular embodiments. In some embodiments the second transmissionmethod is a beam forming transmission method which involves formingbeams as a function of channel quality feedback information receivedfrom said wireless terminal.

In some implementations of the first exemplary method both the basestation and the wireless terminal include multiple antennas. In one suchimplementation said second transmission technology is a multiple-input,multiple-output technique.

In accordance with various embodiment of the present invention, the basestation includes one or more routines in memory which operate as achannel segment scheduler and a resource allocator. The channel segmentschedule assigned channel segments to wireless terminals, e.g., inresponse to channel selection and/or channel assignment request signalsreceived from one or more wireless terminals. The resource allocator isresponsible for allocating resources between channels corresponding todifferent technologies and may reassign resources from a channelcorresponding to one technology to a channel corresponding to anothertechnology, e.g., in response to channel selection signals or channelassignment requests received from one or more wireless terminals.

In some implementations of the first exemplary method the step ofoperating one of the base station and mobile to select a communicationschannel includes selecting the first communications technology when saidmeasurement indicates a first rate of wireless terminal movement, saidfirst communications technology providing at least one of a higherfrequency diversity and a time diversity than a second communicationschannel and selecting the second communications channel corresponding tothe second communications technology when said measurement indicates asecond rate of wireless terminal movement, the second rate of wirelessterminal movement being lower than said first rate of wireless terminalmovement, the second communications technology providing a high spatialdiversity than is available from the first communications channelcorresponding to the first communications technology.

In some implementations of the first method, the step of operating oneof the base station and mobile to select a communications channelincludes operating said one to perform the steps of: selecting a channelin said plurality of channels which provides a higher frequency or timediversity than is available from the non-selected communicationschannels in said plurality of channels when changes in channelconditions are occurring at a rapid rate; and selecting another channelin said plurality of channels which provides higher spatial diversitythan said channel which is selected when changes in channel conditionsare occurring at said rapid rate, said another channel being selectedwhen changes in channel conditions are occurring at a slow rate, saidslow rate being a rate which is slower than said rapid rate.

One or more of the plurality of channels used in various embodiments bya base station may be fixed, periodic and/or dynamically generated.Various combinations of channels and types of channels, e.g., fixed anddynamically created, are also possible. In some embodiments at leastsome of said plurality of fixed communications channels are periodic innature with different combinations of channels existing at differentpoints in time, the combination of channels exiting at any point in timebeing predictable due to the periodic nature of the communicationschannels. In some implementations of the exemplary method, the basestation periodically reallocates resources between channelscorresponding to different technologies based on a predeterminedschedule. In various implementations the base station reallocatesresources between channels corresponding to different technologies basedon signals received from one or more wireless terminals. As part of themethod of the invention, the base station may create a channelcorresponding to a particular technology in response to a signalindicating a request for a channel using the particular technology froma wireless terminal. The base station sometimes maintains channelscreated in response to signals from a wireless terminal for a period oftime which is a function of at least one signal received from saidwireless terminal which requested the channel.

In some implementations of the method of the invention the base stationincludes multiple antennas, a first set of wireless terminals whichinteract with said base station in one such embodiment includes multiplereceive antennas while a second set of wireless terminals which interactwith said base station each include only a single receive antenna. Insuch an embodiment mobile nodes including multiple receive antennasusing a communications channel corresponding to a MIMO technology duringsome points in time with which they interact with said base station andusing channels corresponding to technologies which require only a singlereceive antenna at different points in time when interacting with saidbase station. In the case where some wireless terminals include only asingle receive antenna, those terminals interact with the base stationusing one or more channels corresponding to a technology which does notrequire multiple receive antennas.

In various embodiments of the first exemplary method the base station toreallocates communications resources from one of the plurality ofcommunications channels to a communications channel using a differentcommunications technology as a function of the signal received from saidwireless terminal.

In some embodiments where the generated signal transmitted to the basestation by the wireless terminal indicates the channel selection to thebase station, the method includes operating the wireless terminal toselect between the plurality of communications channels based on themaintained set of communications quality information to thereby selectthe channel corresponding to the transmission technology which providesthe better transmission characteristics to said wireless communicationsterminal. In some implementations of the first exemplary method, thebase station operates to alter the use of communications resources toincrease the amount of resources used to generate a communicationschannel using the technology corresponding to a communications channelselected by the wireless terminal.

While described primarily in the context of an OFDM system, the methodsand apparatus of the present invention, are applicable to a wide rangeof communications systems including many non-OFDM and/or non-cellularsystems.

In various embodiments nodes described herein are implemented using oneor more modules to perform the steps corresponding to one or moremethods of the present invention, for example, signal processing,message generation and/or transmission steps. Thus, in some embodimentsvarious features of the present invention are implemented using modules.Such modules may be implemented using software, hardware or acombination of software and hardware. Many of the above describedmethods or method steps can be implemented using machine executableinstructions, such as software, included in a machine readable mediumsuch as a memory device, e.g., RAM, floppy disk, etc. to control amachine, e.g., general purpose computer with or without additionalhardware, to implement all or portions of the above described methods,e.g., in one or more nodes. Accordingly, among other things, the presentinvention is directed to a machine-readable medium including machineexecutable instructions for causing a machine, e.g., processor andassociated hardware, to perform one or more of the steps of theabove-described method(s).

Numerous additional variations on the methods and apparatus of thepresent invention described above will be apparent to those skilled inthe art in view of the above description of the invention. Suchvariations are to be considered within the scope of the invention. Themethods and apparatus of the present invention may be, and in variousembodiments are, used with CDMA, orthogonal frequency divisionmultiplexing (OFDM), and/or various other types of communicationstechniques which may be used to provide wireless communications linksbetween access nodes and mobile nodes. In some embodiments the accessnodes are implemented as base stations which establish communicationslinks with mobile nodes using OFDM and/or CDMA. In various embodimentsthe mobile nodes are implemented as notebook computers, personal dataassistants (PDAs), or other portable devices includingreceiver/transmitter circuits and logic and/or routines, forimplementing the methods of the present invention.

What is claimed is:
 1. A method of operating a base station comprisingthe steps of: transmitting signals corresponding to a plurality ofdifferent communications channels in parallel, at least two of saidcommunications channels corresponding to different communicationstechnologies; receiving information, from a wireless terminal whichsupports said plurality of different communications channels; andselecting between said communications channels corresponding todifferent communications technologies for use in communicating with saidwireless terminal as a function of a rate of motion of said wirelessterminal.
 2. The method of claim 1, further comprising: controllingallocation of resources to said communications channels in response tothe selection of a communications channel corresponding to a particularcommunications technology.
 3. The method of claim 2, wherein saidcommunications channels include communications channel segments; whereinsaid resources are resources used to provide communications channelsegments, said resources including bandwidth, time or power; and whereinsaid controlling the allocation of resources is responsive to channelrequest information and creates a communications channel using acommunications technology corresponding to the particular communicationstechnology of the selected communications channel.
 4. The method ofclaim 2, wherein said allocation of resources is done by using resourcesfrom a communications channel implemented using a first communicationstechnology and reassigning the resources to a communications channelusing a second communications technology when the demand for acommunications channel using the second communications technologyincreases, said first and second communications technologies beingdifferent.
 5. The method of claim 1, wherein said step of selecting acommunications channel includes selecting between at least two differentcommunications channels implemented using different communicationstechnologies.
 6. The method of claim 1, wherein the base stationreallocates resources between communications channels corresponding todifferent communications technologies based on signals received from oneor more wireless terminals.
 7. The method of claim 6, wherein the basestation creates a communications channel corresponding to a particularcommunications technology in response to a signal indicating a requestfor a communications channel using the particular communicationstechnology from a wireless terminal.
 8. The method of claim 7, whereinthe base station maintains said created communications channel for aperiod of time which is a function of at least one signal received fromsaid wireless terminal which requested the communications channel. 9.The method of claim 1, wherein the base station includes multipleantennas, a first set of wireless terminals which interact with saidbase station including multiple receive antennas, a second set ofwireless terminals which interact with said base station including asingle antenna, wireless terminals including multiple receive antennasusing a communications channel corresponding to a MIMO technology duringsome points in time with which they interact with said base station andusing communications channels corresponding to communicationstechnologies which require only a single receive antenna at differentpoints in time when interacting with said base station.
 10. The methodof claim 9, wherein wireless terminals which include only a singlereceive antenna interact with said base station using one or morecommunications channels corresponding to a communications technologywhich does not require multiple receive antennas.
 11. A base stationcomprising: means for transmitting signals corresponding to a pluralityof different communications channels in parallel, at least two of saidcommunications channels corresponding to different communicationstechnologies; means for receiving information from a wireless terminalwhich supports said plurality of different communications channels;means for selecting between said communications channels, correspondingto different communications technologies, for use in communicating withsaid wireless terminal as a function of a rate of motion of saidwireless terminal; and means for controlling allocation of resources tosaid communications channels in response to the selection of acommunications channel corresponding to a particular communicationstechnology, said resources including bandwidth, time or power.
 12. Thebase station of claim 11, further comprising: wherein saidcommunications channels include communications channel segments.
 13. Thebase station of claim 12, and wherein said controlling the allocation ofresources is responsive to channel request information and creates acommunications channel using a communications technology correspondingto the particular communications technology of the selectedcommunications channel.
 14. A base station comprising: a transmitter fortransmitting signals corresponding to a plurality of differentcommunications channels in parallel, at least two of said communicationschannels corresponding to different communications technologies; areceiver for receiving information from a wireless terminal whichsupports said plurality of different communications channels; and aselection module for selecting between said communications channelscorresponding to different communications technologies for use incommunicating with said wireless terminal as a function of a rate ofmotion of said wireless terminal.
 15. The base station of claim 14,further comprising: a resource allocation control module for controllingallocation of resources to said communications channels in response tothe selection of a communications channel corresponding to a particularcommunications technology.
 16. The base station of claim 15, whereinsaid resource allocation control module is responsive to channel requestinformation and creates a communications channel using a communicationstechnology corresponding to the particular communications technology ofthe selected communications channel.
 17. A base station comprising: aprocessor configured to control said base station to: transmit signalscorresponding to a plurality of different communications channels inparallel, at least two of said communications channels corresponding todifferent communications technologies; receive information from awireless terminal which supports said plurality of differentcommunications channels; and select between said communications channelscorresponding to different communications technologies for use incommunicating with said wireless terminal as a function of a rate ofmotion of said wireless terminal.
 18. The base station of claim 17,wherein the processor is further configured to control said base stationto: control allocation of resources to said communications channels inresponse to the selection of a communications channel corresponding to aparticular communications technology.
 19. The base station of claim 18,wherein said communications channels include communications channelsegments; wherein said resources are resources used to providecommunications channel segments, said resources including bandwidth,time or power; and wherein controlling the allocation of resources isresponsive to channel request information and creates a communicationschannel using a communications technology corresponding to theparticular communications technology of the selected communicationschannel.
 20. A non-transitory computer readable medium embodying machineexecutable instructions for controlling a base station, thenon-transitory computer readable medium comprising: instructions whichwhen executed by a processor cause said base station to transmit signalscorresponding to a plurality of different communications channels inparallel, at least two of said communications channels corresponding todifferent communications technologies; instructions which when executedby said processor cause said base station to receive information from awireless terminal which supports said plurality of differentcommunications channels; and instructions which when executed by saidprocessor cause said base station to select between said communicationschannels corresponding to different communications technologies for usein communicating with said wireless terminal as a function of a rate ofmotion of said wireless terminal.